Device for controlling exposure from a radioactive source

ABSTRACT

A device is disclosed for controlling the exposure from a radioactive source by removably positioning a radiating pellet within a bore in a shielding material in a handle-operated telescoping torch arrangement which can be stored in disassembled form in a protective container.

United States Patent Inventor George A. Seward l2 Flaunden Lane, Bovingdon, England Appl. No. 756,970 Filed Sept. 3, 1968 Patented May 25, I971 DEVICE FOR CONTROLLING EXPOSURE FROM A RADIOACTIVE SOURCE 9 Claims, 3 Drawing Figs.

US. Cl 250/106, 250/108 Int. Cl 62" 5/02 Field of Search ..250/l06 (S) 56] References Cited UNITED STATES PATENTS 3,147,383 9/1964 Prest. 250/IO6X 3,191,037 6/1965 Noble et al. 250/106 3,393,317 7/1968 Spencer 250/106 Primary Examiner-William F Lindquist Assistant Examiner-Davis L. Willis Att0rneyLaurence R. Brown ABSTRACT: A device is disclosed for controlling the exposure from a radioactive source by :removably positioning a radiating pellet within a bore in a shielding material in a handle-operated telescoping torch arrangement which can be stored in disassembled form in a protective container.

DEVICE FOR CONTROLLING EXPOSURE FROM A RADIOACTIVE SOURCE The present invention concerns apparatus for the storage and use of radioactive source material particularly in relation to the radiographic examination and testing of materials and structures.

Such apparatus conventionally comprises a heavily shielded container in which the radioactive source can safely be stored and transported from place to place, a torch by means of which the source can be removed from the container and placed in operational position whilst protecting the operator from the harmful effects of the radiation of the source, and a castle which can be mounted at the operational position and into which the torch is inserted when it is removed from the container.

The invention contemplates improved apparatus of the foregoing type providing greater safety for the operator and greater flexibility in the use of the apparatus.

According to the invention-there is provided a device for the controlled exposure of a radioactive source said device comprising a body of radiation-shielding material having a longitudinal bore therein communicating with an exposure aperture in the outer surface of said body, a carrier for radioactive source material slidably disposed in said bore, and means for displacing said carrier into and out of a position in which a source carried by said carrier is exposed through said aperture.

In a preferred form of the apparatus according to the invention the torch and castle are separate items connectable together by means of a bayonet-type coupling such that the completion of the coupling action is effective to permit or cause exposure of the source which is otherwise retracted into the radiation shield body of the torch. By any one of a variety of means the extent of exposure of the source relative to the body of the torch can be arranged to be selectively variable. One simple and convenient way of achieving this is to have a number of castles which differ in the effective length of the bayonet socket in each and a single torch constructed in such a manner that the extent of movement of the pins or pegs which coact with the bayonet socket during coupling of the torch to a castle determines the extent of movement of the source from its retracted position to its exposed position. Thus, for example, with three different castles the effect of coupling one torch to each castle in turn could conveniently be arranged to produce one-quarter, one-half and full exposure of the source respectively. Alternatively a single castle may be provided with two or more pairs of bayonet sockets of different effective socket lengths.

The end of the torch body from which the source is projected to expose it may present a flat surface with a central aperture or it may be frustoconical with the aperture at the apex of the frusto cone thereby permitting a wider angle of effective radiation from the source when exposed, the size of the aperture in relation to the degree of retraction into the body of the torch behind such aperture determining the angle of radiation when the source is in retracted position. To provide for flexibility of application of a standard form of torch in this latter respect, the end portion of the torch body may be detachably secured so that either a fiat-faced or cone-faced end portion may be fitted to the torch, before the source is inserted, in dependence upon the intended use of the torch. For the greater safety of the operator, and other personnel, the end portion of the torch may be so constructed that a body of shielding material is automatically moved into and out of the aperture as the source is respectively retracted and moved to exposed position. For example, the end portion of the torch body may be slotted axially and two slides of shielding material fitted into the slot to completely fill the slot, the two slides being so linked or mechanically interrelated with the mechanism for moving the source from its retracted position so as to move radially away from each other to form the exposure aperture between them either as a preliminary operation before the source can be advanced from its retracted position or as a consequence of the source being advanced from its retracted position.

By such means the source can be completely shielded until it is exposed in use and because of this amount of shielding material required to be present in the storage container can be proportionately reduced whilst maintaining the same degree of safety.

The drawings accompanying the present specification illustrate a preferred form of the apparatus of the invention,

FIG. ll being a sectional view of a torch with the source retracted,

FIG. 2 being a side view of the torch at to the view of FIG. 1 with part of the casing broken away and showing, in dotted lines, a castle in position ready for coupling and exposure of the source, and

FIG. 3 being a sectional view through a storage container with the torch in position inside it.

The torch of FIGS. 1 and 2 comprises a detachable handle portion I and a spring-loaded telescopic body portion 2 having a central bore 3. The telescoping parts of the body 2 are secured together by a bolt 4 operating in a slotted hole 5 and a spring 6 normally keeps the outer casings 7 and 8 of the two parts of the body separated by a distance d. The casing 7 surrounds a cylindrical block 9 of depleted uranium-shielding material through which part of the central bore 3 extends. A rod 10 also of depleted uranium-shielding material is a sliding fit in bore 3 and carries at its forward end a radioactive source pellet 11 which in the normal nonoperational state of the torch occupies the position shown well inside the block of shielding material 9.

Referring to FIG. 2, the castle 12 shown in dotted lines comprises-a block of suitable material such as brass with a sleeve extension 13 in which are formed bayonet slots 14 for cooperation with pins 15 projecting from the sides of the body of the torch. The castle has a bore 16 which is inwardly lipped at 17 and in which the casing 7 of the torch is a sliding fit. From the position shown in FIG. 2, where the forward end of casing 7 abuts against the lip 17, rotation of the handle portion of the torch brings the pins 15 into register with the bayonet slots 14 and further movement of the handle in a direction towards the castle telescopes the two parts of the torch body together compressing the spring and moving the rod 10 and source 11 along the bore 3 until the source projects proud of the end face of the castle. The extent of such projection depends upon the length of the bayonet slot in relation to the dimension d of FIG. 1 and in the example illustrated these are equal. The container shown in section in FIG. 3 comprises a cylindrical outer casing in two interfitting parts 20 and 21 which lock together the upper part 21 having lugs 22 to which a carrying handle 23 is attached. The lower part 20 has a cover plate 24 with a central aperture to receive the torch body and a second aperture at one side to receive the torch handle. Beneath the plate '24 are mounted a large mass 25 of depleted uranium-shielding material having a blind bore in register with the central aperture in plate 24 and a :sheet metal cylinder 26 in register with the second aperture and lodged between the sidewall of the lower container part 20 and the mass 25. A locating shelf 27 locates the mass 25 with its bore in register with the central aperture of plate 24.

Iclaim:

1. A device for the controlled exposure of a radioactive source said device comprising a body of radiation-shielding material having a longitudinal bore therein communicating with an exposure aperture in the outer surface of said body, a carrier for radioactive source material slidably disposed in said bore, and means for displacing said carrier into and out of a position in which a source carried by said carrier is exposed through said aperture wherein said carrier comprises a rod of radiation-shielding material which is slidably fitted in said bore and said displacing means forms a handle for the device longitudinally aligned with said carrier whereby an operator holding said handle is shielded from the radioactivity of the source by said body and by said carrier.

2. A device as claimed in claim 3 wherein said shielding material is depleted uranium.

3. A device as claimed in claim 1 wherein said displacing means is arranged to be locked selectively in any one of a number of different positions in each of which the source is exposed through said aperture to differing extents.

4. A device as claimed in claim 1 including a castle member adapted to receive said body and to be releasably coupled thereto by a bayonet coupling arranged to serve as the means for locking said displacing means in position.

5. A device as claimed in claim 4 wherein said castle member is formed with a plurality of pairs of bayonet sockets of different effective socket lengths and said displacing means is provided with a pair of bayonet pins insertable selectively in any pair of said sockets the arrangement being such that the selection of a particular pair of sockets determines the extent of exposure of the source when the displacing means is locked in position.

6. A device as claimed in claim 4 wherein said castle includes abutment means serving to arrest insertion of said body into said castle with the pins of the bayonet coupling displaced longitudinally of the body from the locked position and said displacing means is arranged to be displaced longitudinally of said body against said spring loading to engage said pins in the locked position defined by the sockets or selected sockets of the coupling and thereby displace said carrier into exposed position.

7. A device as claimed in claim 1 wherein said aperture is formed in an end face of said body and such end face is contoured to be frustoconical with the aperture at the apex of the frusto cone.

8. in combination with a device as claimed in claim 1 a container having a block of radiation-shielding material therein provided with a blind bore to receive the body of said device.

9. A device for the controlled exposure of a radioactive source said device comprising a main body part of radiationshielding material having a bore therein communicating with an exposure aperture in the outer surface of said body part, a handle part extending into said bore the inner end of which handle part serves as a carrier for radioactive source material, said handle and body parts being relatively displaceable between at least one first position in which source material carried by said carrier is positioned outside said main body part and a second position in which said material is positioned inside said main body part, spring means arranged to urge said handle part to maintain said material in said second position and a holder adapted to receive said body part and to cooperate with said body and handle parts so as to lock said body and handle parts together with said material in said first position. 

2. A device as claimed in claim 3 wherein said shielding material is depleted uranium.
 3. A device as claimed in claim 1 wherein said displacing means is arranged to be locked selectively in any one of a number of different positions in each of which the source is exposed through said aperture to differing extents.
 4. A device as claimed in claim 1 including a castle member adapted to receive said body and to be releasably coupled thereto by a bayonet coupling arranged to serve as the means for locking said displacing means in position.
 5. A device as claimed in claim 4 wherein said castle member is formed with a plurality of pairs of bayonet sockets of different effective socket lengths and said displacing means is provided with a pair of bayonet pins insertable selectively in any pair of said sockets the arrangement being such that the selection of a particular pair of sockets determines the extent of exposure of the source when the displacing means is locked in position.
 6. A device as claimed in claim 4 wherein said castle includes abutment means serving to arrest insertion of said body into said castle with the pins of the bayonet coupling displaced longitudinally of the body from the locked position and said displacing means is arranged to be displaced longitudinally of said body against said spring loading to engage said pins in the locked position defined by the sockets or selected sockets of the coupling and thereby displace said carrier into exposed position.
 7. A device as claimed in claim 1 wherein said aperture is formed in an end face of said body and such end face is contoured to be frustoconical with the aperture at the apex of the frusto cone.
 8. In combination with a device as claimed in claim 1 a container having a block of radiation-shielding material therein provided with a blind bore to receive the body of said device.
 9. A device for the controlled exposure of a radioactive source said device comprising a main body part of radiation-shielding material having a bore therein communicating with an exposure aperture in the outer surface of said body part, a handle part extending into said bore the inner end of which handle part serves as a carrier for radioactive source material, said handle and body parts being relatively displaceable between at least one first position in which source material carried by said carrier is positioned outside said main body part and a second position in which said material is positioned inside said main body part, spring means arranged to urge said handle part to maintain said material in said second position and a holder adapted to receive said body part and to cooperate with said body and handle parts so as to lock said body and handle parts together with said material in said first position. 